Micellar Mole Fraction Research Articles

Mixed micellization analysis of tri-substituted SAIL and amphiphilic drug mixture in aqueous/salt media at diverse temperatures

Abstract The present work aimed to study the mixed micellar behaviour of a tri-substituted imidazolium based surface-active ionic liquid (SAIL), 1-tetradecyl-2,3-dimethylimidazolium bromide [C14bmim][Br], with a drug Nortriptyline hydrochloride (NOT) in the water/salt (Na2SO4) medium using surface tension measurements (298.15 K) alongwith conductivity measurements (298.15K–313.15K). Lower experimentally obtained cmc values compared to their ideal values suggest that the investigated amphiphiles interact strongly. The values of micellar mole fraction (X 1) based on the several proposed models (Rubingh, Motomura, and Rodenas) and the ideal micellar mole fraction (X id ) were assessed, and the predicted outcomes indicate that NOT has a significant contribution to the formation of mixed micelles, which increases as the [C14bmim][Br] mole fraction is increased. The negative values of micellization’s Gibbs free energy (ΔGm 0) between the examined amphiphiles were an indication of spontaneous mixed micelle formation. Micellar changes in entropy (ΔSm 0) and enthalpy (ΔHm 0) were also computed and discussed. Using surface tension measurements, surface-active parameters like surface tension at cmc (γ cmc ), minimum surface area per IL molecule (A min), maximum surface excess concentration (τ max), effectiveness of surface tension reduction (π cmc ), and cmc of mixed system have been estimated. The results showed an improved adsorption and micellization properties of these mixtures which will surely contribute to the tremendous rise of these mixed systems in drug delivery applications.

Micelle formation and physico-chemical variables for the sodium dodecyl sulfate/cetylpyridinium chloride and their mixture in aqueous propranolol hydrochloride drug solvent: Conductivity and theoretical analysis

Herein, study of both single and mixed micelle development of an anionic surfactant sodium dodecyl sulfate (SDS) and a cationic surfactant cetylpyridinium chloride (CPC) in propranolol hydrochloride (PPH) drug medium has been performed using a conductometric technique at different temperatures and compositions. The critical micelle concentration (CMC) along with degree of ionization (g) were assessed from the specific conductivity (κ) versus [surfactant] plots. Within the concentration of surfactant studied, a single CMC was achieved in the situations of pure and mixed surfactant micellization. The CMC and g values have been noticed reliant on the employed drug concentrations, variations of mole fractions of the mixture of surfactants and experimental temperature. For the micellization of single SDS/ CPC surfactants in aq. PPH drug medium, PPH drug causes delayed micelle development which has been detected as the upsurge of CMC values of SDS/CPC in PPH drug media. For the association of SDS/ CPC surfactants in aq. PPH drug medium, the CMC values experienced a lessening with the growth of study temperature. At a fixed temperature, the experimental CMC values, of the SDS + CPC mixture, endure a decline through the upsurge of mole fractions of CPC (α1), attain a minimum value and the CMC values tend to enhance at and above α1= 16.2 × 10-5. The ideal critical micelle concentrations (CMCid) are detected always as higher values than experimental CMC up to the α1= 10.8 × 10-5. The -β values and |β| > |ln(CMC1/ CMC2)| for the present study reveal that the interaction among the amphiphiles under analysis is synergistic. The negative free energy (-ΔGmO) of micellization were obtained throughout the study. The enthalpy (ΔHmO) and entropy (ΔSmO) of micellization reveal the presence of hydrophobic interaction as the principal type of interaction among the studied constituents. The negative excess free energy (ΔGex) values inferred that stable mixed micelles are formed for the mixture of SDS + CPC in aq. PPH drug medium. The micellar mole fractions (both experimental and ideal values), activity coefficients of components in mixed micelles as well as enthalpy–entropy compensation parameters were also measured and illustrated. It is possible that the knowledge gained from the current analysis may be used to enhance pharmaceutical formulations, drug delivery carriers, along with drug act proficiency.

Impact of ceftriaxone sodium on tetradecyltrimethylammonium bromide & cetyltrimethylammonium bromide mixture: Conductivity and theoretical investigation

The formation of mixed micelle of tetradecyltrimethylammonium bromide (TTAB) & cetyltrimethylammonium bromide (CTAB) mixture has been carried out in appearance of ceftriaxone sodium trihydrate (CTS) drug having different concentrations over a temperature range of 298.15 to 323.15 K, keeping a break of 5 K. The CMC of pure and mixture of surfactants were observed to be reliant on the concentration of drug. The CMC values of TTAB + CTAB mixture lie in between that of pure TTAB & CTAB. The larger deviation of CMC of TTAB & CTAB mixture from the corresponding ideal CMC (CMCid) at higher mole fraction (α1) of CTAB signify stronger interaction amid TTAB and CTAB at higher bulk α1 of CTAB. The negative excess free energy (ΔGexRub) values reveal the stable form of micelle and the stability was attained to be enhanced by the rise of α1 of CTAB. The interaction parameter (β) also reveals the attractive interaction amongst the studied species of surfactants. The micellar mole fraction (X1Rub), as well as its ideal (X1id) values, experience an augmentation by the rise of α1, which reveal that the contribution of CTAB increase with the raise of α1. The Gibbs free energy of micellization (ΔGm0) reveals a spontaneous association of both pure and mixed systems. The enthalpy (ΔHm0) and entropy (ΔSm0) of micellization reveal that the micellization is exothermic in nature, while the recommended forces are hydrophobic interaction, along with weak electrostatic interactions. The values of intrinsic enthalpy also reveal the micelle’s stability, thereby, formed. Degree of dissociation (g), compensation temperature, etc., were also reported.

Synthesis and mixed micellization characteristics of pyrrolidinium SAILs in association with Sarcosine

Herein, conductivity and surface tension measurements have been applied to investigate the mixed micellization of [C12C1pyrr][Br]/[C14C1pyrr][Br] in water/Sarcosine media at various temperatures (298.15–313.15K). The cmc* and cmc were used to define the degree of interaction between the two SAILs. In the presence of the amino acid Sarcosine, values of CMC are clearly lesser than the corresponding values in an aqueous media. The well-known Clint, Rubingh, Motomura, and Rodenas models have been employed to estimate the magnitudes of mixed micellar mole fractions (X1), interaction parameter (β), and activity coefficients (f1andf2). The results obtained indicate the effective participation of [C14C1pyrr][Br] in mixed micellization. At 298.15 K, tensiometric measurements have also been carried out to confirm the outcomes from conductivity analysis for all of the examined systems. The surface parameters which have been elucidated from surface tension measurement include surface tension at cmc(γcmc), surface pressure (Πcmc), surface excess (Γmax) and minimum area per molecule (Amin), etc. All of the estimated results indicate an attractive interaction between the components of the studied mixed system.

Unravelling the Interactions Prevailing in Mixed Micellar System of Surface-Active Ionic Liquid and Cationic Surfactant

The investigation of mixed micellar behavior of surface-active ionic liquid (SAIL) i.e. 1-butyl-3-methylimidazolium hexadecyl sulfate [C4mim][HS] with cationic surfactant cetyltrimethylammonium bromide (CTAB) has been done to explore the type of interactions prevailing in SAIL/Surfactant mixed system. Thus, the conductometric measurements are performed at (298.15, 308.15 and 318.15) K for various mole fractions of [C4mim][HS]. Different theoretical models like Clint, Rubingh, Motomura and Rodenas have been applied to understand mixed micellar behavior of SAIL/Surfactant mixed system. The value of critical micelle concentrations (cmc), micellar mole fraction based upon various models, ideal critical micelle concentrations (cmc*), interaction parameter (β) and thermodynamic parameters have been evaluated for the mixed systems. The variations of various parameters with respect to temperature and mole fractions give insight to sort of interactions present in studied system.

Micellar and Surface Properties of Cationic-Cationic Binary Surfactant Mixtures: Synergistic Interactions and Solubility Enhancement of Anthracene

The micellar and surface behaviors of decylammonium chloride (DACl) in presence of L-alanine hydrochloride decylester (L-ADE) and L-alanine hydrochloride dodecylester (L-ADDE) at various mole fractions were investigated by conductivity and surface tension measurements. From the conductivity measurements, the critical micelle concentration (CMC), the degree of counter-ion ionization (α) and standard Gibbs energy of micellization (ΔG°mic) were investigated for both pure and binary mixtures. The molecular interaction parameter (β) and the micellar mole fraction (XmDACl) for mixed micelle formation by DACl/L-ADE (C10-C10) and DACl/L-ADDE (C10-C12) were calculated using the regular solution equation proposed by Rubingh. The ideal values of CMC (CMCideal) and the micellar mole fraction (XmDACl(ideal)) were also obtained for mixed micelle according to the pseudo phase theoretical models. The negative β values showed that there were synergistic interactions for all compositions of DACl/L-ADE and DACl/L-ADDE mixed systems. From the surface tension measurements, adsorption parameters such as the surface excess concentration (Γmax), minimum surface tension at the CMC, efficiency in the surface tension reduction (pC20), standard Gibbs energy of adsorption (ΔG°ads), and minimum area per head group of a molecule (Amin) in pure, mixed and their ideal values were also determined. The results indicated that the synergism and attractive interactions in the studied binary mixtures depend on the chain length of the cationic L-alanine ester and their mole fractions in the mixed system. The solubilization capacity of pure DACl and its mixed system with L-ADE and L-ADDE towards anthracene were determined and discussed in terms of molar solubilization ratio (MSR). Based on the MSR values, the solubility enhancement was found for anthracene in DACl/L-ADE and DACl/L-ADDE mixed systems.

Transition from antagonistic to synergistic interaction in mixed micellar system by increase in alkyl chain length of alkyl trimethylammonium bromide

Herein, the electrical conductivity technique used to measure the critical micelle concentration (cmc) for pure cationic surfactants (Dodecyl/cetyltrimethylammonium bromides) and phenothiazine drug (Promethazine hydrochloride), as well as their different mole fractions in 10−3 ​mol/kg 1-methyl-3-octylimidazolium chloride (C8mim.Cl) at different temperatures. By using the cmc values the regular solution theory used to evaluate the micellar mole fraction for DTAB/CTAB-PMT mixed systems. The clint's model used to calculate the ideal critical micelle concentration (cmc∗) that helps to evaluate the ideal micellar mole fraction for studied mixed systems, both explain the deviation from ideality. In addition, interaction parameter βm helps to confirm the nature of interaction (either antagonistic or synergistic) for the studied systems. The calculated parameters confirm a transition in the binding nature from antagonistic to synergistic with the increase in alkyl chain length of cationic surfactant i.e., component of the binary mixed system. The ease of micellization for the studied systems discussed by the standard Gibb's energy of micellization (ΔGm0), as well as the standard enthalpy and standard entropy of micellization were (ΔHm0) and (ΔSm0), respectively to discuss the stability of the studied systems.

The interaction of the surface active ionic liquid with nonionic surfactants (Triton X-100 and Triton X-405) in aqueous solution by using tensiometry method

The synergistic interactions of the surface active ionic liquid (1-dodecyl-3-methylimidazolium bromide, IL) with non-ionic surfactants TritonX-100 (TX-100) and TritonX-405 (TX-405) were investigated in aqueous solution at various mole fractions by using the surface tension technique at 298.15 K. In this work, the pendant drop method was used for surface tension measurement of solutions. The surfactant properties such as critical micelle concentration (CMC), micellar mole fractions (X1Rub), interaction parameter (βm), and activity coefficients of components in the mixed micelle (f1Rub and f2Rub) were calculated by theoretical Clint and Rubingh models. Also, surface and adsorption parameters, maximum surface excess values (Γmax), minimum area per molecule (Amin), surface tension at CMC (σCMC), and surface pressure at the CMC (πCMC) values have been estimated in (TX-405/TX-100 + IL + water) systems. The synergistic effects operating in these amphiphile mixtures were confirmed by the negative values of the interaction parameter. Generally, the CMC value of surfactant solution increases with the addition of ionic liquid in the mixture. It was demonstrated that IL can be judiciously used at different mole fractions for modifying the physicochemical properties of (TX-100 and TX-405). Different thermodynamics parameters were computed for mixtures and were also discussed in detail. The Gibbs free energy change of micellization (ΔGmo), the standard Gibbs energy of adsorption (ΔGado) and the excess free energy of micellization (ΔGexRub) values have been estimated at different compositions. The calculation of thermodynamic parameters shows that the micellization process is spontaneous and becomes more favorable with addition of the non-ionic component in mixture.

Interactions of tricyclic antidepressant drug chlomipramine hydrochloride with imidazolium based surface active ionic liquid in aqueous solution

Tricyclic antidepressant drug, Chlomipramine hydrochloride (CLP) with surface active ionic liquid (SAIL), 1-octyl-3-methylimidazolium chloride, was investigated using electrical conductivity. Various theoretical models were employed to calculate various interaction parameters and thermodynamic parameters. Different mole fractions of CLP with SAIL were studied to evaluate the critical micelle concentration (CMC) using electrical conductivity measurements. The change in Gibbs free energy of micellization, change in enthalpy of micellization, change in entropy of micellization, micellar mole fraction, χ1, of the CLP, and the interaction parameter, β, activity coefficients ƒ1 and ƒ2were calculated. The χIdeal and χ1 values were observed to increase on increasing the mole fraction of CLP from 0.4 to 0.6. This may be an indication of drug molecules being adsorbed on the micellar surface. As a result the mixed system (CLP and SAIL) were found to form stable mixed micelles.

The Assembly of the Mixture of Two Ionic Surfactants in Polyols Media at Variable Temperatures: Combined Conductivity and Theoretical Investigations

AbstractHerein, the aggregation phenomena of the two cationic amphiphiles, the hexadecyltrimethylammonium bromide (CTAB), and tetradecyltrimethylammonium bromide (TTAB), has been investigated in the presence of monosaccharide (glucose) and disaccharide (maltose) at varying compositions and temperatures. The critical micelle concentration (cmc), degree of ionization (g), and several thermodynamic properties have been estimated applying the conductivity measurement technique. To explore the consequence of additives on the mixed micellization of TTAB + CTAB, glucose as monosaccharide having two concentrations (1% & 5% (w/w) glucose) and maltose as disaccharide containing single concentration (1% (w/w)) have been employed. Together with the mixture of TTAB and CTAB, investigation of the physicochemical parameters of pure amphiphiles in glucose and maltose solutions was quantified. The efficiency of the additives in depressing the cmc values followed the order: 1 (w/w) % maltose >5 (w/w) % glucose >1% (w/w) glucose. The ideal cmc (cmcid), activity coefficients, and β values suggested the synergistic attraction (attractive force) between these two surfactants. By utilizing the Rubingh model, the evaluated micellar mole fractions of CTAB (α1) coupled with the ideal mole fraction () imply the increase of the contribution of CTAB in the mixed micellization with rising the α1 values. The values of the negative excess free energy () implied the stability of the mixed micelle formed. The changes in standard enthalpy (ΔH°m) and changes in standard entropy (ΔS°m) of micellization reveal the presence of different modes of interactions like electrostatic, ion‐dipole, H‐bonding, and hydrophobic interactions among the studied components.

Investigation of aggregation behavior of ionic surfactant mixture in crystal violet dye solution at different temperatures and solvent compositions: Conductivity and theoretical approach

The conductometric measurement technique was utilized to have an in-depth knowledge on the aggregation behavior of a mixture of two ionic surfactants – sodium dodecyl sulfate (SDS; a common anionic surfactant) and cetyltrimethylammonium bromide (CTAB; a cationic surfactant), in crystal violet (CV) and CV + ethanol (5 and 10% (w/w)) solution media. The related micellar and thermodynamic parameters of the mixed system have been assessed and presented in this paper. The cmc values of pure SDS/CTAB, & their mixture in presence of CV dye, were observed to decrease and thus the insertion of CV favors the micellization of pure and mixed micelle. Also, the cmc values of the mixture of SDS & CTAB undergo a drop with increasing the concentration of CTAB at a specific temperature and these cmc fall in the middle of the detected cmc of SDS & CTAB micelles in all the media studied. The observed values of cmc are lower in magnitude in comparison to the ideal cmc and the numerical values of the interaction parameter (β) are negative, which manifests the existence of attractive interaction between SDS and CTAB surfactants in presence of CV dye. The cmc values are also dependent on the fluctuation of experimental temperature. The micellar mole fraction of component 1 (CTAB) in SDS + CTAB mixture (X1Rub) and the ideal micellar mole fraction (X1id) was obtained to be relatively greater than the related stoichiometric mole fraction (α1) of component 1 (CTAB). The activity coefficients (f1Rub and f2Rub) remained below unity in all test cases, suggesting an attractive interaction in the mixed micellar system. The obtained thermodynamic parameters demonstrate that the single and mixed micellization phenomena are spontaneous and the main driving forces are hydrophobic and exothermic in nature.

Mixed micelle formation between a surface active ionic liquid and tricyclic antidepressant drugs (imipramine hydrochloride and amitriptyline hydrochloride)

Mixed micelle formation between surface active ionic liquid (1-dodecyl-3-methylimidazolium bromide, IL) and two amphiphilic drugs consisting of imipramine hydrochloride (IMP) and amitriptyline hydrochloride (AMT) were investigated in different mole fractions at 298 K using electrical conductivity measurements. The experimental results of mixed antidepressant drugs (IMP and AMT) with ionic liquid in aqueous solution indicated that CMC values decreased with the addition ionic liquid in mixture. Also, the CMC values in AMT/IL system are comparatively lower than those found in IMP/IL system, which indicates that the formation of mixed micelle is more favorable in presence of AMT. The different theoretical models (Clint, Rubingh, Motomura and Rodenas) were used to evaluate the micellar mole fractions (Xi), interaction parameter (βm) and activity coefficients of components (f1 and f2) in the mixed micelle. In both studied systems, the values of interaction parameter suggest the synergistic effects in mixed state. Activity coefficients are less than unity which means non-ideal mixing. Also, the excess free energy of micellization (ΔGex) values have been estimated using activity coefficients at different compositions. This parameter not only confirm that mixed micellization is spontaneous in nature but also is extra stable than individual micelle.

Comparison of the interaction between propranolol hydrochloride (PPL) with anionic surfactant and cationic surface active ionic liquid in micellar phase

In this study, the interaction in binary mixtures comprising an amphiphilic drug (propranolol hydrochloride, PPL) and ionic surfactants (N-lauryl sarcosine sodium, NLS and 1-dodecyl-3-methylimidazolium bromide, SAIL) was investigated in micellar phase using conductometric technique in aqueous solution at 298.15 K. SAIL is a cationic surface-active ionic liquid with a specific critical micelle concentration(CMC). To identify the influence of polar head groups in interaction between components, the surfactants with the same alkyl chain length (C12) but with oppositely charged head groups were selected (NLS: anionic and SAIL: cationic). The deviation of experimental critical micelle concentration (CMCexp) from the corresponding ideal values of CMC (CMCid), the micellar compositions (X1 and X2), the mutual interaction parameter (βm), activity coefficients of the components in the mixed micelle (f1 and f2) and thermodynamic parameters have been calculated using different proposed theoretical models like Clint, Rubingh, and Motomura. The interaction parameter (βm) is negative values at all compositions for two systems (with two levels of values), showing attractive interactions between components. In comparison between the NLS/PPL and SAIL/PPL systems, the NLS/PPL system shows stronger micelle formation capability, smaller CMC values and stronger synergistic effect. The determined values of the micellar mole fraction of surfactant (X1) obtained from theoretical models signify the considerable contribution of surfactant in surfactant(1)/PPL(2) mixed micellization. Further, conductometry measurements indicate that the extent of counterion binding (α) of mixed micelles for SAIL/PPL system are higher than those found for NLS /PPL system.

Effect of low levels of hydrotropes on micellization of phenothiazine drug

Interactions within mixtures of the phenothiazine drug promethazine hydrochloride (PMH) and cationic hydrotropes ortho-toluidine hydrochloride (o-TDH) and para-toluidine hydrochloride (p-TDH) were investigated at different ratios and temperatures via conductometry to understand various physicochemical properties. Critical micelle concentration (cmc) was less than values of cmcid (cmc in ideal mixed system), indicating significant interaction among the studied constituents in solution mixtures. The cmc of pure PMH was also determined by measuring the surface tension for comparison. A variety of micellization thermodynamic parameters (Gibbs free energy [ΔG 0 ], change in standard enthalpy [ΔG 0 ], and change in entropy [ΔG 0 ]) were computed using conductometry. The micellar mole fraction (X 1 , X 1 , and X 1 ) of hydrotropes estimated by various theoretical models (Rubingh, Rodenas, and Motomura) was assessed, and the results showed a greater contribution of hydrotropes in mixed micelles along with their values increasing via an increase in mole fraction (α1) of hydrotropes (o-TDH/p-TDH). Negative β values suggest extremely favorable attractive interaction/synergism, as declines occurred in the whole quantity of amphiphile used for the desired purpose, leading to a drop of expenditure along with ecological concern. Obtained activity coefficients (f1 and f2) were always beneath unity, meaning nonideality was found between PMH and o-TDH/p-TDH. Like the conductivity method, the UV-visible and FT-IR techniques also demonstrate the interaction between the PMH and o-TDH/p-TDH.

Aggregation Behavior of Mixed Micellar System of Dodecyl Sulfate‐Based Surface‐Active Ionic Liquids and Anionic Surfactant in Aqueous Media

AbstractMixed micellization behavior of dodecyl sulfate‐based ionic liquids, i.e., 1‐propyl‐3‐methylimidazolium dodecyl sulfate [C3mim][DS] and 1‐hexyl‐3‐methylimidazolium dodecyl sulfate [C6mim][DS] with sodium dodecyl sulfate (SDS), is investigated at (298.15, 308.15, and 318.15) K in aqueous medium. For this, the conductometric measurements are carried out to evaluate the critical micelle concentrations (cmc), ideal critical micelle concentration (cmc*), degree of counterion dissociation (g), thermodynamic parameters, micellar mole fraction of ionic liquids, and interaction parameter (β) of the mixed system based on the different proposed models given in the literature. Further surface tension measurements have been carried out to confirm the value of cmc obtained via a conductivity study for all the studied systems at 298.15 K. Other surface parameters, such as surface tension at cmc (γcmc), surface pressure (ᴨcmc), surface excess (Γmax), and minimum area per molecule (Amin), have also been evaluated for both the systems.

Association behavior of the amphiphilic drug and sodium p-toluenesulfonate mixtures: Effect of additives

The interaction between an amphiphilic phenothiazine drug—promethazine hydrochloride (PMT)—and anionic hydrotrope sodium p-toluenesulfonate (NaTS) mixtures was analyzed and the effect of different mole fractions (α1) of NaTS along with the variation of temperature was also investigated in three different media, water/NaCl (50 mmol.kg−1)/urea (U) (300 mmol.kg−1), using a conductometric method. Drug PMT is mainly utilized to cure allergic symptoms. From the study of pure components along with solution mixtures of components, various physicochemical parameters were evaluated and discussed thoroughly. The obtained results show that the experimental critical micelle concentrations (cmcs) are less than their corresponding ideal cmc (cmcid) values, showing the interaction amongst the constituents (PMT and NaTS). Mixing of dissimilar kinds of amphiphiles has an opportunity to bring about additional valuable acts owing to their attractive interaction. As hydrophobicity of the PMT + NaTS mixtures increased, therefore the cmc values remarkably decreased. The degree of dissociation (g) of the studied system was also evaluated and found to increase with a rise in temperature and decrease via an increase in α1 of NaTS. In salt (NaCl) solution, cmc and g-value of PMT and PMT+ NaTS at all compositions were decreased compared with an aqueous system while in U solution their value was found to be greater than in aqueous solution. Various theoretical models were also considered to estimate the fraction of hydrotrope in mixed micelles PMT + NaTS, the parameter is named the micellar mole fraction (X1Rb (Rubingh model), X1Rd (Rodenas model) and their ideal value is X1id), and the obtained value shows the higher composition of NaTS in mixed micelles along with their value increasing through an increase of α1 of NaTS in the solution mixture. One other parameter, called the interaction parameter (β), was observed as negative throughout the study, also proving the attractive interaction/synergism amongst the components of the solution mixture (PMT + NaTS). Assessed activity coefficients were all below one, showing the nonideality of the studied system. Several thermodynamic parameters of micellization, such as Gibbs free energy (ΔGm0), enthalpy (ΔHm0), and entropy (ΔSm0) have been determined in all studied media and compositions. UV–visible spectroscopy also confirmed the interaction amongst PMT and NaTS. Scanning electron microscope (SEM) images depicted a clear-cut interaction of PMT and NaTS interaction. The outcomes from the current study are significant in the expansion of the operative model drug delivery process.

Synergistic Solubilization of Phenanthrene by Mixed Micelles Composed of Biosurfactants and a Conventional Non-Ionic Surfactant

This study investigated the solubilization capabilities of rhamnolipids biosurfactant and synthetic surfactant mixtures for the application of a mixed surfactant in surfactant-enhanced remediation. The mass ratios between Triton X-100 and rhamnolipids were set at 1:0, 9:1, 3:1, 1:1, 1:3, and 0:1. The ideal critical micelle concentration values of the Triton X-100/rhamnolipids mixture system were higher than that of the theoretical predicted value suggesting the existence of interactions between the two surfactants. Solubilization capabilities were quantified in term of weight solubilization ratio and micellar-water partition coefficient. The highest value of the weight solubilization ratio was detected in the treatment where only Triton X-100 was used. This ratio decreased with the increase in the mass of rhamnolipids in the mixed surfactant systems. The parameters of the interaction between surfactants and the micellar mole fraction in the mixed system have been determined. The factors that influence phenanthrene solubilization, such as pH, ionic strength, and acetic acid concentration have been discussed in the paper. The aqueous solubility of phenanthrene increased linearly with the total surfactant concentration in all treatments. The mixed rhamnolipids and synthetic surfactants showed synergistic behavior and enhanced the solubilization capabilities of the mixture, which would extend the rhamnolipids application.

Influence of additive on the aggregation behavior of drug and cationic hydrotrope aniline hydrochloride mixtures: a physicochemical assessment

AbstractWe investigated the influence of an additive (50 mmol kg–1 NaCl/300 mmol kg–1 urea [U]) on the aggregation of amphiphilic promethazine hydrochloride (PMH) drug and cationic hydrotrope–aniline hydrochloride (AnHCl) mixtures at various temperatures and ratios. The drug PMH is mostly used for the treatment of allergic symptoms. The obtained critical micelle concentration (cmc) values are well below the cmcid (ideal cmc) value, which confirms interactions between components PMH and AnHCl in the solution mixture. The micellar mole fraction (X1Rub, X1Rod, and X1id) of the first component (AnHCl) was evaluated using different models, which suggested greater involvement of AnHCl in mixed micelles (as expected); besides, the obtained micellar mole fraction values increase with increase in the mole fraction (α1) of AnHCl. The interaction parameter (β) values obtained were negative, which confirms attractive interaction or synergism among the components. Activity coefficients ( [AnHCl] and [PMH]) values are always found below one confirming the nonideality as well as attractive interaction between the components. Different physicochemical parameters evaluated suggested attractive interaction between the components (PMH and AnHCl) in all studied solvents; however, in salt media, the interaction increases to some extent, whereas in urea media, it decreases to some extent. Diverse thermodynamic parameters (Gibbs free energy [ΔGm0], enthalpy [ΔHm0], and entropy [ΔSm0]) of micellization were computed and discussed separately. The excess free energy ( ) values of all systems were negative, suggesting higher stability of formed mixed micelles as compared with singular‐component micelles.

Influence of Electrolyte and Temperature on the Aggregation Behaviour of Mixed System Consisting Drug and Anionic Surfactant

At present work, the interaction of amphiphilic drug promazine hydrochloride (PMZ) with anionic surfactant sodium dodecyl sulfate (SDS) and imipramine hydrochloride (IMH) with anionic surfactant dioctyl sulfosuccinate sodium salt (AOT) in the absence and presence of 50 mmol.kg−1 inorganic salt is investigated in aqueous medium at different temperatures. For this, conductometric measurements were carried out to evaluate the critical micelle concentrations (CMC) of drug and surfactant. Ideal critical micelle concentration (CMC id) and interaction parameter (β) has also been evaluated. The deviations obtained in values of CMC and CMC id indicate the interaction between drug and surfactant. Other micellar mole fraction parameters such as X1 Rub (Rubingh), X1 Mot (Motomura), X1 Rd (Rodenas) and X1 ideal (ideal mole fraction) are also evaluated based on different proposed models. Other thermodynamic parameters of micellization such as, standard free energy of micellization , standard enthalpy of micellization , and standard entropy of micellization are also evaluated based upon the equations already present in literature to understand the interactions prevailing in the studied systems.

Theoretical Approaches on the Synergistic Interaction between Double‐Headed Anionic Amino Acid‐Based Surfactants and Hexadecyltrimethylammonium Bromide

AbstractTheoretical investigations on the micellization of mixtures of (i) amino acid‐based anionic surfactants [AAS: N‐dodecyl derivatives of aminomalonate, −aspartate, and ‐glutamate] and (ii) hexadecyltrimethylammonium bromide (HTAB), were carried out at different mole ratios. Variation in the theoretical values of critical micelle concentration (CMC), mole fraction of surfactants in the micellar phase (X), at the interface (Xσ), interaction parameters at the bulk/interface (βR/βσ), ideality/nonideality of the mixing processes, and activity coefficients (f) were evaluated using Rubingh, Rosen, Motomora, and Sarmoria‐Puvvada‐Blankschtein models. CMC values significantly deviate from the theroretically calculated values, indicating associative interaction. With increasing mole fraction of AAS (αAAS), the magnitude of the (βR/βσ) values gradually decreased, considered to attributable to hydrophobic interactions. With increasing αAAS, the micellar mole fraction of HTAB (X2) decreased insignificantly and X2 values were higher than those compared to AAS for all combinations, due to the dominance of HTAB in micelles. Micellar mole fraction at the ideal state of AAS () differed from micellar mole fraction of AAS (X1), indicating nonideality in the mixed micellization process. Gibbs free energy of micellization ( ∆Gm) values are more negative than the free energy of micellization for ideal mixing (), indicating the micellization process is spontaneous. With increasing αAAS, the enthalpy of micellization (ΔHm) and entropy of micellization (ΔSm) values gradually increased, which indicates micellization is exothermic. The different physicochemical parameters of the mixed micelles are correlated with the variation in the spacer length between the two carboxylate groups of AAS.